Abstract: The seismic responses of the piles in a wave-current fieldare studied by theoretical analysis and finite element simulation.Besides the wave-current force and hydrodynamic pressure on thepiles in the wave-current field, the results of the model testshow that the vortex-induced lateral force should also be considered. Thefinite element simulation of a platform with four piles in thewave-current field under seismic action is carried out. It is shown thatthe seismic responses of the piles are magnified by water. Except for theacceleration along piles, the relative displacement and shear force andmoment are increased significantly under the combined action of the wave-current force andthe vortex-induced lateral force. And it is also indicated that thefailure at the bottom of piles occurs easily under the seismic action.